Grinding wheel trueing device



April 14, 1953 A. AEPPLI 2,634,556

GRINDING WHEEL TRUEING DEVICE Filed Feb. 18, 1947 2 SHEETS-:SHEET l a as April 14, 1953 A. AEPPLI' 2,634,556

GRINDING WHEEL TRUEING DEVICE Filed Feb. 18, 1947 2 SHEETSSHEET 2 l/vuewrom Patented Apr. 14, 1953 GRINDING"WHEEL THU'EING :Albert sAeppli, Zurich. Switzerland, assignor to Maag-Zahnrader und- MaschinenrA. Gsizuticib.

Switzerland Application February 18, 19. 3? SerialiNmi7Z3322 Switzerland March .1, 11946 My invention relates to improvements in devices for trueing grinding wheels or discs, e. g. .fcrming part of gear-grinding machines. In :eontradistinction to trueing devices known in the art, the grinding wheel i automatically 'trued whenever a .certain number of functional operations of the machine have been performed, which operations bear on the wearing of the grinding disc. Such operations may include the readjustment of the disc, in'accordance with the wear undergone .in grinding, by small uniform :rates 'atrcer'tain intervals of time. Other operations, "essential for trueing, may consist of carmin-g out of a certain grinding operation, e. g. the finishing of a number of tooth flanks of a gear wheel in' a 'gear grinding machine. The individual functional operations may be numerically addedby means oia counter and the trueing operation released by the latterxaftershaving attained the predetermined number.

Suitable arrangements may be made for not counting up the functions of re-adjusting the grinding disc by the trueing rate, and of resuming the grinding operation only after having finished the trueing operation and the i e-adjustment of the disc brought about thereby.

'Two forms of invention as applied to a geargrinding machine, are .illustrated, .in the drawings, inwhich Fig. -1 is 'aschematical View, partly insection,

of the grinding disc and motor, the disc-readjusting gear, and the device for trueing the disc on the basis of the readjust-ins functions .of the machine,

Fig. .2 is :a sectionalview throu h the counter :for the read-justingfunctions of the machine,

Fig.3 is a view of the contactor disc 23, 2d of F 2.,

Fig. 4 a diagrammatic side elevation of the machine.

In Fig. 1,1a grinding wheel 2, which serves for working the tooth-flanks of gear wheel I, is mounted in a sleeve 3. The electric motor l driving wheel 2, is :provided with two operative shaft ends. One of the latter drives the shaft 8 over a jack-shaft 5, a bevel gear 6 and a worm gear I. Shaft 8, on one hand, operates the eleiments for resetting the grinding wheel by the amount of wear incurred in grinding or trueing, and, on the other hand, brings about the automatic trueing of the grinding wheel under predetermined conditions.

For resetting purposes, acam disc 9 is keyed to sh'aft 8. One end of a bell-crank lever I!) is -dropped 'into the .notch of disc 9 at each revolu- .-3 :.Claims. (01. fil

revolution of disc 23.

tion oi shaft 8. The ilugeiend all pf letter 1.0 is "spaced quite close to the narrow :lateral working face of the grinding wheel'2. Thesaid first end of lever '0 is :provided witha ,contactor lisspaced quite close to the :countencontaotor 213.. According to the rate of wear of disc 2, either the end "ll contacts "the latter or contactor i112 abuts against contactor 13. *In the latter case,.ran:elec-- tromagnet 1 4 raises latch :125 iOf fa Iriction clutch IS, an eccentric '1'! thus making one i'revohition and slightly turning the :ratchet "wheel 19 by means of a pawl l8. Ratchet wheel 13 :ieeds grinding wheel .2 at a certain small Irate, e. g. 0.90004 inch, by means of :the :fine threads .20

:(Fig. 2). Such feed cycle is repeatedfuntil'ithe wear of wheel 2 has "been compensated.

Ratchet wheel 1 9 is coupled to :a second ratchet wheel 22 by means of 'if-rictionally operating leaf springs 2 Aeontactor disc 13 iEig. 3) is mounted insulated on wheel22 'and is-circumferentially provided with spaced contactors 24. A current-lead brush Z5 continuously contac'ts disc 23, while a second -brush 26 contacts one of the contactors 2'4 when disc 23 isrotated. In the arrangement accordin to Fig. 3, such latter contact is established six times during one When ratchet Wheel 19, for example, possesses teeth, brush 23 will be engaged "by a contactor :stud .24 after every '20 steps of pawl '1'8,'each such step being brought about by one oi-said teeth.

A circuit then is completed across the contacts 21, 28, to and the electromagnet "29 which Tin its turn, now, makes-the contacts 31-33. Contact'or 33 serves as a "holding con'tactor for the e'leotro-magnet 29. As soon as "contactor "33' is closed, 29 remains :c'losed until contact "30 "is closed. The carriage 4-1, on which the-generating slide N34 with the work I is mounted on shaft H33 during the grinding-operation 'is slowly fed in the direction of its longitudinal axis. In the terminal positions of carriage 41, adog 48 or 48 is abutted against a follower 50 which is guided by a rod 5]. Follower '50 contact "the make-and-break 54, 55 breaking "contactors "2"! or 2% and making either con-tactor 5-2, 53, thus completing the circuit of magnet 38by way or "break 32. Magnet '38 attracts the armature '39,

thus making contactors '35"3-1. The "circuit over contactors 36, dl and magnet 34 now is completed, and the latter disengages the latch '42 of the friction clutch 4-3. The eccentric .disc '44, therefore, is turned through one revolution iby the continuously rotating ssha'ft 8, and actuates the vdiamendstudded.ztrueing 45 iby may .of

the arm 46. Thus the operative marginal zone of wheel 2 is faced once. By raising the magnet armature 3 5a, contactor 35 and thus also contactors 3l-33 are broken after disengaging clutch latch 42. The circuit of magnet 38 thus is interrupted by contactor 32 for the time being, and. its armature 39 would be retracted under the action of a spring 5? biasing the valve piston so, thus breaking contactor 35-31. Piston 55, however, is moving to the left in Fig. 1 only slowly, being subjected to a braking action. The cylinder Bl, namely, is filled with oil which, upon armature 39 being attracted, is displaced through the valve 66 into the chamber 58. When, now, spring 51 enters into action, valve 60 is closed, and the oil is permitted to flow slowly through the narrow bore 59 back into cylinder 6i. Before, now, armature 39 has covered a substantial portion of its deflection, bell-crank lever i9 drop-s into the recess of the continuously rotating disc 9, and makes contact l2, l3, thus bringing about a re-adjustment of grinding wheel v2. At the same time, break 62 is made, and

magnet ll makes contact 49 which feeds magnet 38 for a short time. Such impulse, however, is suificient to restore armature 3.5 into its fully closed position. The cycle of operation of spring 5?, starting with the slow backward pushing of the piston 56 and ending when the magnet 39 is energized, is started anew, until a further impulse, set forth by bell-crank lever Hi, reaches .magnet 33.

During such period of resetting wheel 2, contact 35 also remains made and magnet 53 is energized and drops the pawl 64 into an interdental space of ratchet wheel 22, so that the latter and contact disc 23 are stopped. This means that the resetting functions have not been counted up by the amount wheel 2 has been trued. When the operative lateral workng face of grinding wheel 2 again has reached its normal position,

the current pulses through bell-crank lever iii cease (though its movement continues), armature 39 no longer is attracted, and spring 5'! is given time to push piston 55 into its outer terminal position, i. e. to the left as shown in Fig. 1. Contacts 353!, magnet 53 and pawl 6 thus .are opened and the subsequent resettings again are counted up by the advance of contact studs 25. Carriage 41 is moved by a pressure piston 59 which is controlled by a valve ll, 72. The latter .--is moved by means of the two dogs 38, E9 of carriage 4?, which displace the follower 5t and .thus the rod 5! in either of their terminal positions. -valve pistons H, 12 t the left or to the right.

Rod by means of arm 85 moves the The ducts i3, 74 thus alternatingly are opened to the cylinder 70 for the supply or discharge of oil.

During the trueing operation and the Wheelresetting brought about thereby, grinding, of course, has to be discontinued. To this end, the feed of carriage i? in one terminal position is blocked in the following manner. During the grinding operation, interrupter 38, 39 remains open, piston 56 opens the pressure oil supply 55, and plunger 66 is pushed upward. When, now, the moment for trueing has arrived, switch 31-33 first is closed, as described above. As soon as carriage 41 has arrived at a terminal position, magnet 38 is energized over contactors 52 or 53, piston, 56 is displaced to the right and shuts off oil feed 65, spring 6'! pushes plunger 65 downward, and the pin 68 drops into the cylinder 15 to the left or right of piston 15,.whereby the control valve H, 12 and thus the pressure piston 69 are blocked. Such blocking continues until the grinding wheel again has reached its normal operating position, upon which the emission of pulses on the part of lever I9 ceases, armature 35 drops off, and the pressure oil raises plunger 66 with pin 69, thus releasing the control for the movement of the carriage.

The counters or counting trains also may be of a design and construction different from those shown in the form illustrated; it only being essential for the invention that they bring about the effects set forth above.

What I claim and desire to secure by Letters Patent, is:

1. An automatic grinding wheel turning machine for gear grinding machines, comprising, in operatively assembled combination, a rotatable shaft on which said grinding wheel is mounted, rotary driving means drivingly connected to said grinding wheel shaft, a rotatable cam disc operatively connected with said grinding wheel driving means to be rotated thereby, a pivotally mounted feeler lever, means operably connected with said lever for moving said lever to periodically engage said grinding wheel to test the wear thereof, a shifting means having an operation initiating part located in position to be engaged by said lever, upon a predetermined pivoting movement of said feeler lever taking place due to wear of the grinding wheel for engaging and axially shifting the grinding wheel by'uniform steps, a counting mechanism having an operation control part located in a position to beengaged by said shifting means upon completion of a predetermined shifting movement for counting the shifting steps, a grinding wheel trueing tool, means operatively connected with said grinding wheel shifting means and operable upon completion of a predetermined number of shifting steps for moving said trueing tool into operative relation with the grinding wheel, and means operably connected with said trueing tool for restoring the tool to inoperative position after completion of a trueing operation.

2. An automatic grinding wheel trueing device as defined in claim 1 and including a locking member operative during a trueing operation to engage and lock said counting mechanism and prevent operation thereof until completion of the trueing operation. I

3. In, operatively assembled, combination with a grinding machine having a work-carriage, actuating members for moving said work-carriage, a rotatably mounted grnding wheel, an automatic grinding wheel trueing device for gear grinding machines, comprising a rotatably mounted gr nding wheel, means for driving the grinding wheel, a rotatable cam disc operat'vely connected with said grinding wheel driving means to be rotated thereby, a pivotally mounted feeler lever operated by said cam to periodically engage said grinding wheel to test the wear thereof, a shifting means having an operation initiating part positioned to be engaged by said lever upon a predetermined pivoting movement of said feeler lever e to wear of the grinding Wheel for axially shifting the grinding wheel by uniform steps, a counting mechanism having a counting operation control part positioned to be engaged by said shifting means upon completion of a predetermined shifting movement of the grinding wheel for causing said shifting steps to be counted, a grinding wheel trueing tool, means operatively connected with said grinding wheel shifting means and operable upon completion of a predetermined number of shifting steps for moving said trueing tool into operative relation with the grinding Wheel, means operably connected with said trueing tool for restoring the tool to inoperative position after completion of a trueing operation, and means for engaging and locking said work-carriage actuating members to prevent movement of the work-carriage during a trueing operation.

ALBERT AEPPLI.

References Cited in the file of this patent Number 6 UNITED STATES PATENTS Name Date Johnston Apr. 23, 1901 Maag June 5, 1917 Guild et a1. Aug. 18, 1931 Heald et a1. Jan. 19, 1932 Haas Oct. 18, 1932 Guild Mar. 14, 1933 Geier et a1. Nov. 7, 1933 Lewis et a1 Jan. 31, 1939 Greiner et a1 Mar. 5, 1940 Galloway Feb. 26, 1946 

